Here’s what September weather could look like in southern Ontario

By

Published August 3, 2025 at 2:01 pm

Here’s what September weather could look like in southern Ontario

As the season gradually shifts into fall, September is expected to bring cooler-than-usual temperatures and a wet start for most of  Ontario.

For those squeezing in final patio days or planning early autumn outings, here’s what the month could look like.


According to the Farmers’ Almanac, Sept. 1 to 5 will begin with heavy thunderstorms, followed by sunny skies and mild conditions.

From Sept. 6 to 13, thunderstorms in the north and steady rain in the south will usher in a cooler air mass.

Sept. 14 to 20 is forecast to be rainy and chilly, while Sept. 21 to 23 may bring a short stretch of sunny but cool weather.

The month will close with sun in the north and rain in the east from Sept. 24 to 30, alongside fall-like temperatures across the region.

The Farmers’ Almanac predicts average temperatures near 13 C, about 2 C below normal for southern Ontario.

Rainfall is expected to total 120 mm, with above-average precipitation in the north and average amounts in the south.

Whether you’re ready for sweater weather or hoping for a late-season warm-up, September looks to bring an early taste of fall.

INsauga's Editorial Standards and Policies

PollView All

Last 30 Days: 45,321 Votes
All Time: 1,445,551 Votes

WIN A $100 GIFT CARD

Subscribe to INsauga’s daily email newsletter for a chance to win a $100 Amazon gift card.